The production of epoxy resins from polyhydric phenols and epihalohydrins requires the etherification (coupling) of the phenol and the epihalohydrin and the dehydrohalogenation (epoxidation) of the coupled chlorohydrins intermediate using aqueous inorganic hydroxides. For the epoxidation of the coupled chlorohydrin intermediate, the problem is to contact the inorganic hydroxide, which has almost no solubility in the organic phase, with the chlorohydrin intermediate, which has almost no solubility in the aqueous phase, to generate an epoxy resin with very low chlorohydrin content without excessive hydrolysis of the epihalohydrin.
Reciprocating-plate columns (such as Karr columns) are well known for use in liquid-liquid extraction and consist of a vertical column which contains a set of perforated plates attached by one or more common shafts. A motor drives the shaft, which reciprocates up and down to provide agitation and break up the dispersed phase into small droplets. The heavy phase moves down the column while the light phase moves up the column. In this way, the two insoluble phases are brought into contact to allow enhanced mass transfer between the two phases. For extraction, reciprocating plate columns are cited has having more uniform shear patterns than columns with rotating agitators, which leads to more uniform drop size distribution, higher volumetric capacity and better turndown capability. By using a reciprocating-plate column in this invention, complete epoxidation can be achieved with low epichlorohydrin yield losses.